SPServices and PreSaveAction

In my NewForm (WSS3), I'm hiding some fields using jquery and running some SPServices for lookups etc. Now I'm trying to use PreSaveAction to copy an entry field, encode() special characters, then put it into the hidden field and save.

Problem is that PreSaveAction doesn't fire at all. Any suggestions for how I might get it working? Does SPServices have its own version of this function? Even my test code doesn't fire the alert.

You don't want PreSaveAction to be wrapped in $(document).ready, but I don't think it should matter. PreSaveAction is a built-in SharePoint function which doesn't do anything by default. If you add your own script to your own version of it, it will fire
when you try to save the form.

Oh I just noticed. It looks like when using the presaveaction to populate a hidden field, it doesn't get obtain the data on save. The new data only appears to save when the field is visible. Any way to get around this?

Dan's right, you can make this work. Fields which are disabled won't be sent with the commit, and there are some other instances as well. What you'll need to do is re-enable the field in the PreSaveAction so that it is submitted.